The invention relates to a breast pump.
Breast pumps comprising a non-return valve were on the market which comprised, in a pre-chamber situated towards the milk collector and joined to the valve body, a flap freely movable through this pre-chamber. Thus, the pre-chamber was only closed by this flap against the milk collector, this flap being held by tabs of the chamber wall bend inwardly and forming the connecting device when some peripheral openings were freed. However, such a construction is difficult to clean and, therefore, did not meet the hygienic requirements. Moreover, the flap was practically not guided centrally within the chamber so that it was enabled to take an inclined position whereupon proper operation was not ensured.
Now, breast pumps of the kind described at the outset have become known from U.S. Pat. No. 4,929,229, for example. There was an simple plug connection for the flap in the middle of the front surface of the valve provided in them, thus being easy to be detached and cleaned. A problem lies in that, although the milk is sucked off in the biological rhythm of a sucking baby, very different quantities of milk result from it which have to be conveyed to the milk collector, in most cases in the form of a connected receptacle. In the past, this resulted in various drawbacks in operation of such a breast pump. Namely, with a large quantity of milk, the milk could reach the pump unit which could easily be destroyed or at least was not usable for a long time up to repair or dismantling and cleaning.
Investigations of the applicant have shown that the aforementioned problem had various reasons which acted even the kind mentioned at the outset in such a way that damaging or soiling the pump unit is no longer possible. According to the invention, this is achieved by any of the characterizing clauses of claims 1, 8 or 15 and/or 20.
First of all, it has been recognized that, although the valve according to U.S. Pat. No. 4,929,229 solved the hygienic problem, it permitted only a reduced elasticity to the flap due to its central connection device. Certainly, there was some prejudice of those in the art that uniform closure of the plurality of throughput openings provided in the prior art could be achieved by a central connecting device. However, this prejudice turned out to be unfounded according to the investigations of the applicant. On the contrary, by providing a flap being hinged at the edge of the front surface, i.e. eccentrically, it is endowed with an increased flexibility. For it has been found that with a central arrangement of the connecting device, the flap has only the free radius along which it can exhibit its flexibility. In this way, the flap became, however, somewhat stiff, thus forming a not inconsiderable flow resistance even with the throughput opening being freed. By the construction according to the invention, in contrast, the freely flexible length of the flap is increased, and the flap obtains properties of a greater suppleness and elasticity so that it engages tightly the respective throughput opening under the action of suction, but frees under load the throughput opening practically without any resistance even with a small quantity of milk.
In order to solve the problem of the connection to the valve body, it would be possible, in fact, to provide a plug, analogously to the prior art, about within the region of the hinge which could be plugged into a plug opening on the front surface of the valve body. However, in accordance with exemplary embodiments of the present invention, cleaning is easily effected by detaching the fastening flange from the valve body, while, at the same time, the connecting device cannot have any detrimental effect to the hinge.
Just in the case where the flap has an enhanced elasticity and suppleness, in correspondence with the cited embodiment according to the invention, a single throughput opening cannot be made with any dimension, because the supple flap could jam in it during the suction stroke of the pumping unit. Therefore, an embodiment according to the present invention is particularly advantageous, because in this way a large throughput cross-section is ensured without the necessity to make an individual throughput opening too large.
A central connection was provided in the prior art not least because one feared too great an elasticity which could interfere with a proper closure of the respective throughput opening during the suction stroke of the pump unit. By an embodiment according to the invention the finite thickness of the margin surrounding closely the flap effects, in this way, sealing between it and the flap which is quickly sucked into the opening of the margin thus created during the suction stroke. The margin may, in this case, be thickened around the flap, but this is, in general, not necessary.
Certainly, the hinge could be constructed in a variety of ways. However, by an embodiment according to the invention a smooth, and therefore easily to clean, plastic hinge is obtained which can be easily produced integrally with the flap.
In the U.S. Pat. No. 4,929,229, and not only in it, the first branch channel runs about as a prolongation of the discharge channel, i.e. obliquely downwards. Therefore, a partition wall was inserted to inhibit any direct connection of the two channels. In practice, however, this was not very effective, because when milk dammed up at the valve it could reach the branch channel anyway and could not be removed from it. In accordance with an exemplary embodiment however, milk drains automatically even then without reaching the pump unit, if the quantity of milk should be as large that the valve is unable to let it through in a short time.
Within the scope of an exemplary embodiment of the invention it is sufficient, as such, if only some section of the first branch channel is upward directed, but it is preferred, in accordance with a further exemplary embodiment of the invention, that drainage into the milk collector can be achieved without any additional measure.
For it has been found that part of the problem is created by an inappropriate suction effect of the pump unit itself. However, by the measures according to an exemplary embodiment of the present invention one gains control not only of the problem of too large quantities of milk, but an additional effect of an, in case, more gentle suction less uncomfortable for the user will be obtained especially when also the features of alternate embodiments are provided which enable adaptation of the effective suction power to the user.